Aluminum alloys with improved intergranular corrosion resistance properties and methods of making and using the same

Abstract

Disclosed herein are embodiments of aluminum-based alloys having improved intergranular corrosion resistance. Methods of making and using the disclosed alloy embodiments also are disclosed herein.

We claim: 
     
       1. An aluminum alloy, comprising copper, magnesium in an amount ranging from 0.27 wt % to 8 wt %, a rare earth element (REE) component selected from cerium, lanthanum, or a combination thereof, wherein the total amount of the rare earth element (REE) component ranges from greater than 1 wt % to 4 wt %; iron, and balance of aluminum and trace impurities, wherein the aluminum alloy has an Al 11 REE 3  intermetallic phase, wherein Al is aluminum and the REE is cerium, lanthanum, or a combination thereof, and wherein at least 40% of all copper and at least 60% of all iron present in the aluminum alloy is contained in the Al 11 REE 3  intermetallic phase. 
     
     
       2. The aluminum alloy of  claim 1 , wherein the aluminum alloy comprises copper in grain boundaries of the aluminum alloy and wherein 80% of any such copper present is contained in the Al 11 REE 3  intermetallic phase. 
     
     
       3. The aluminum alloy of  claim 1 , wherein the REE is cerium. 
     
     
       4. The aluminum alloy of  claim 1 , wherein the Al 11 REE 3  intermetallic phase comprises an atomic % of copper and an atomic % of the REE that provides a ratio ranging from 2.1:1 to higher than 2.1:1 (copper:REE). 
     
     
       5. The aluminum alloy of  claim 4 , wherein the ratio ranges from 2.1:1 to 3:1. 
     
     
       6. The aluminum alloy of  claim 4 , wherein the ratio ranges from 2.1:1 to 2.6:1. 
     
     
       7. The aluminum alloy of  claim 1 , wherein the alloy comprises one or more intermetallics having a formula selected from Cu(REE)Al 3 , Cu 4 (REE)Al 8 , or Cu 7 (REE) 2 Al 10 . 
     
     
       8. The aluminum alloy of  claim 1 , wherein the copper is present in an amount ranging from 0.1 wt % to 7 wt %. 
     
     
       9. The aluminum alloy of  claim 1 , further comprising titanium in an amount ranging from greater than 0 wt % to 0.3 wt %; and wherein the magnesium is present in an amount ranging from greater than 0.27 wt % to 3 wt % and the iron is present in an amount ranging from greater than 0 wt % to 2 wt %. 
     
     
       10. The aluminum alloy of  claim 9 , wherein the aluminum alloy further comprises an Al-REE-Ti ternary intermetallic phase and wherein the Al-REE-Ti ternary phase comprises an atomic % of titanium and an atomic % of the REE that provides a ratio of REE to titanium ranging from 0.3:1 to higher than 0.3:1. 
     
     
       11. The aluminum alloy of  claim 1 , further comprising silicon, manganese, zinc, chromium, or zirconium. 
     
     
       12. A method for making the alloy of  claim 1 , comprising:
 melting a solid aluminum-based alloy comprising aluminum, copper, iron, magnesium, and titanium and that is free of a rare earth element to provide a molten aluminum-based alloy; 
 adding to the molten aluminum-based alloy a rare earth element (REE) component selected from cerium, lanthanum, or a combination thereof, to form a molten REE-modified aluminum-based alloy, wherein the REE component is added in an amount sufficient to form the Al 11 REE 3  intermetallic capable of isolating an amount of the copper or the titanium present in the molten REE-modified aluminum-based alloy from an aluminum matrix; and 
 allowing the molten REE-modified aluminum-based alloy to solidify, thereby providing a solidified molten REE-modified aluminum-based alloy having increased intergranular corrosion resistance as compared to a solidified aluminum-based alloy that is not modified with an REE. 
 
     
     
       13. The method of  claim 12 , wherein adding the REE changes the chemical composition of grain boundary precipitates within the molten aluminum-based alloy such that the grain boundary precipitates become more anodic than grain boundary precipitates present in a solidified aluminum-based alloy that is not modified with an REE. 
     
     
       14. The method of  claim 12 , wherein adding the REE changes the chemical composition of grain boundary precipitates within the molten aluminum-based alloy such that the galvanic potential difference between the grain boundary precipitates and precipitate free zones and the galvanic potential difference between the grain boundary precipitates and a grain matrix are both less than 0.020V. 
     
     
       15. The method of  claim 12 , wherein the presence of the Al 11 REE 3  intermetallic capable of isolating an amount of the copper or the titanium present in the molten REE-modified aluminum-based alloy from an aluminum matrix is determined using scanning electron microscopy and/or energy dispersive spectroscopy. 
     
     
       16. The method of  claim 12 , wherein the amount of the REE added to the molten aluminum-based alloy ranges from greater than 0 wt % to 4 wt %. 
     
     
       17. The method of  claim 12 , wherein the amount of the REE added to the molten aluminum-based alloy ranges from 0.1 wt % to 1 wt %. 
     
     
       18. A method, comprising forming a coating on a base alloy by depositing the aluminum alloy of  claim 1  on a surface of the base alloy, wherein the base alloy is more susceptible to corrosion than the aluminum alloy of  claim 1 . 
     
     
       19. The method of  claim 18 , wherein depositing comprises cold spray deposition, twin-wire arc deposition, thermal spray deposition, roll bonding deposition, electrodeposition, physical vapor deposition, or additive manufacturing deposition.